The Challenge of Space Flight

Vostok and Mercury were first steps, designed
to explore the concept of manned space flight. Maxime A. Faget, chief
designer of the Mercury spacecraft, summarized their
importance:

Since these flights were initial
efforts, the purpose of the flights was limited to the basic
experience of launching the spacecraft and crew into orbit, having
them remain there for a period of time, and then having them return
safely to earth. These flights were made at low altitude with the
spacecraft barely high enough to avoid appreciable drag from the
upper fringes of the atmosphere. . . . the amount of energy required
for launching was minimized, and the flight was made safer, since the
difficulty of making a reentry maneuver was also minimized. . . .
these flights . . . proved that it was practical for man to fly in
space.4

While providing valuable lessons in the design
and operation of spacecraft, Vostok and Mercury also demonstrated two
different approaches to accomplishing the same tasks.

The rapid onset of multi-gravity forces
accompanying the rocket launch was one of the primary concerns that
faced the two technical teams. During the powered ascent from earth,
crewmembers had to be protected from the increased "g-loads,"
vibration, and noise. It was known, from aircraft and centrifuge
experiments, that human tolerance to increased gravity forces varied
with the duration of exposure and the attitude of the body with
reference to the force. Soviets and Americans agreed that the
reclining position permitted a pilot to absorb heavy acceleration
loads more comfortably than in any other posture.* In the U.S., Faget, William M. Bland, Jr., Jack C.
Heberlig, and their engineering colleagues decided in favor of a
couch contoured to the form of each individual astronaut to protect
him from g-loads. Soviet designers also used the form fitting couch,
and all Mercury and Vostok pilots rode semi-supine in their own
tailor-made seats.5

Once a pilot overcame the initial acceleration
forces of flight, he would encounter the phenomenon of gravity
balanced by centrifugal force, generally called weightlessness or
zero g. Flight physicians contended that the absence of gravity might
affect man's physical and mental performance, but in the
[64] face of limited information, the effect of zero
g was
mainly a topic of speculation. Some medical doctors wondered if the
human organism, tailored to earth's gravity, would continue to
function normally when suddenly deprived of that force. Other
physicians worried about the reaction of particular internal organs
to the succession of changes imposed by acceleration, weightlessness,
and deceleration. Heinz Haber and Otto Gauer, who had studied the
question of weightlessness in Germany, had concluded that more
experimental data were needed to permit a better analysis of the role
of zero g in manned space flight.6

Since it was impossible to duplicate
weightlessness on earth, scientists conducted tests with animals
borne aloft by rockets. In the U.S. in 1947, experimenters began
launching live organisms with V-2 rockets. On 20 September 1951, the
monkey Yorick and 11 mice were recovered after an Aerobee flight to
72 kilometers. From this and two subsequent Aerobee monkey launches,
James P. Henry and David G. Simon concluded that weightlessness and
acceleration forces did not adversely affect the
animals.**7

Soviet rocket engineers and physicians also
sent animals to high altitudes, and their canine experiments led them
to the same conclusions that the Americans had reached with primates
and rodents. At first, the Soviet tests were conducted using
pressurized capsules; then they experimented with dogs wearing
special space suits and traveling in unpressurized cabins. In one
case, Albina and Tsyganka were ejected from the descending launch
vehicle at an altitude of 85 kilometers; both dogs rode safely back
to earth in their space suits and ejection seats. These experiments
convinced the Soviets that acceleration and weightlessness did not
pose impossible barriers to manned flight. The significance of this
conclusion was made clear to the rest of the world when the Soviets
sent Laika into orbit with Sputnik
II on 23 November 1957. Although she
was not returned to earth, Laika ate, barked, and moved about in her
space cabin for seven days without apparent ill
effects.8

* Experiments with
rocket sleds and the centrifuge indicated that pilots could endure
forces 20 times that of the earth's gravity, a load well in excess of
those anticipated in normal flights and above those expected under
emergency conditions.

** Both physicians
played subsequent roles in aerospace medicine. Henry became director
of the animal program in Project Mercury. Simon went on to pilot a
Project Man High balloon to 31 kilometers for a 32-hour study of
man's performance in near space in Aug. 1957.

*** Albina and Tsyganka
were veteran travelers and members of the first group of nine canine
cosmonauts. Subsequently, the Soviet scientists trained eight more
dogs for experimental flight and landing by parachute,